How Do Aircraft Air Conditioning Systems Work?

When aircraft operate through cold winter months and hot summer days, the aircraft HVAC system is important for maintaining the comfort of passengers within the cabin. Beyond temperature control, providing a steady supply of air to the cabin also ensures that there is an optimal amount of pressure within the cabin, all while maintaining hygiene through the cycling of older air. In this blog, we will discuss the aircraft air conditioning system, allowing you to better understand how passengers are kept comfortable throughout a flight regardless of the environment outside.

While most understand the basics of an engine and how it serves to create thrust for propulsion, many may not be aware that it also serves as a major facet of the air conditioner system as well. As engines often create thrust through the combustion of fuel and air mixtures, an immense amount of heat is produced which may be harnessed for various means. One of the ways in which aircraft utilizes the heat of the engine is to install an air assembly with a duct which captures engine air. Known as engine bleed air, this oxygen actually serves as the primary source of fresh, breathable air that is provided to the passengers within the cabin. As such, an endless amount of fresh air can easily be harnessed for the comfort of passengers, all while adding no additional weight to the aircraft system. Typically, the duct is placed within the engine around the low-pressure compressor stage, as this ensures that it is far enough away from the combustion chamber to avoid extreme temperatures and fuel vapors that may be present.

As the air conditioner compressor assembly captures bleed air from the engine, it is cooled down utilizing heat transfer with ram air. The ram air is captured through the ram air inlet duct which is placed near the bottom of the fuselage, and it is at a low temperature that can balance the heat of the engine air. This cooling takes place within the heat exchanger of the aircraft, though the two streams never actually come into contact with one another. As the ram air takes on the heat of the bleed air, it is then expelled from the system through an exhaust air assembly duct. Now that the bleed air has been cooled to a suitable level, it is then transferred through an air cycle machine which further cools the temperature of the air, all while increasing pressure with a turbine air conditioner compressor assembly. As the last steps before air enters the cabin through air supply lines, the bleed air has any excess water vapors removed with a condenser, and it is then sent through a mixing chamber which supplies the air to the cabin.

While pilots receive air through an air louvre that is directly located above the captain, cabin air may be provided through two means. The first air supply line for the passenger cabin is the centralized air conditioning assembly, which is where some passengers may see a vapor passing into the cabin through side wall panels above the windows. The second form of cabin air supply is through each individual air conditioning unit that is placed above the passenger, allowing them to control their individual supply. As carbon dioxide builds up through passenger and crew breathing, it is expelled from the cabin with an exhaust air assembly that ensures that there is optimal recycling. Additionally, filters within the exhaust air assembly function to remove 99.99% of the bacteria and viruses that are within the air as well.

Although air conditioning assemblies may vary from aircraft to aircraft, many use similar components and principles to ensure the safety and comfort of passengers throughout a flight. At RFQ Experts, we can help you procure the air conditioner assembly parts and air supply line components that you need with ease. RFQ Experts is an online distributor of aircraft parts, offering competitive pricing and rapid lead-times for the benefit of all our customers. Get started on the purchasing process today with a personalized quote when you fill out and submit an Instant RFQ form as provided through our website.